The present invention uncovers a digital mirror device (DMD), which comprises an array of single deflectable mirrors with nonparallel axes of deflection. The invention relates to simultaneous processing of different light characteristics, e.g. spectral or polarization specifics, by a single DMD-chip.
The DMD according to the state of the art (Texas Instruments, Hornbeck 1997, U.S. Pat. No. 5,600,383) is made of an isomorphic array of single deflectable mirrors. Moreover, all mirrors are identical with regards to all aspects but their relative position (and address) in the array raster. The mirror deflection axes (MDA) of all single mirrors are parallel in the recent DMD. This is a consequence of functional requirements, where the modulation task of the chip is carried out on a single input beam (comp. FIG. 1). Accordingly, if different specificities of light have to be processed, as e.g. in color generation, this has to be achieved either by sequential processing using a single DMD (color wheel, e.g. Hornbeck, From cathode rays to digital mirrors, TI Tech. Journal, FIG. 53, 1998) or by parallel processing using one DMD per specificity (e.g. Tri Prism Assembly (TPA) with 3 DMDs, each of the primary colors is processed as a dedicated beam.
According to the specific orientation of the MDA (e.g. 45° to the image raster in the original DMD, Hornbeck, cit. above), this original DMD is a stereo-isomer (shows handedness), comp. FIG. 2. The lack of mirror-symmetric function aggravates the combination of two (Bausenwein and Mayer, US2005/0141076) or three (see below) DMDs.
In the simultaneous processing of color, a complex array of prisms (Tri Prism Assembly, TPA) is used in state of the art 3-chip displays (Fielding et al., U.S. Pat. No. 6,250,763 and Hornbeck, cit. above). Due to the stereo-isomeric characteristics, an even-numbered difference of the reflections downstream each DMD has to be used, making the TPA a bulky and expensive structure.
In our previous applications we have coupled two DMDs which have differently oriented MDAs with respect to the array raster (Bausenwein und Mayer, DE10361915, US2005/0141076, US2007/0159680, US2007/0171533) for a 2-channel display system. The two DMDs used in our previous work have a uniform array of identical single mirrors. Each DMD has its mirrors deflect on parallel MDAs. The usage of two different stereo-isomeric DMDs had advantages for the system design, but still required two DMDs.